Overused Antibiotics Cause Havoc Among Nursing Home Patients

Residents suffered adverse reactions even when they didn't take the meds

Action Points

Note that this study of antibiotic use in nursing homes found that nursing homes in the highest tertile of use also had higher rates of adverse events.

Be aware that, though adjustments for case-mix were performed, it is conceivable that some of this result is due to confounding by the fact that some nursing homes cater to sicker patients.

One in eight nursing home residents experienced an adverse event related to antibiotic prescribing, regardless of whether they personally took the antibiotics, researchers reported.

During a 2-year period, residents living in Ontario nursing homes that were in the highest one-third of antibiotic use facilities had a 24% higher risk for having an antibiotic-related adverse event, when compared with those living in the lower two-thirds of the 607 facilities housing over 110,000 residents (adjusted odds ratio 1.24, 95% CI 1.07-1.42, P=0.003), Nick Daneman, MD, MSc, of the University of Toronto, and colleagues reported in JAMA Internal Medicine.

"Antibiotics are one of the most frequently prescribed medications in [nursing homes] where 6% to 10% of residents are taking antibiotics at any given time and more than half receive at least one antibiotic prescription in a single year," Lona Mody, MBBS, MSc, of the University of Michigan Medical School, and Christopher Crnich, MD, of the University of Wisconsin School of Medicine and Public Health, wrote in an editorial in JAMA Internal Medicine. "Much of this use is inappropriate."

To place this study into the scope of U.S. healthcare, Mody and Crnich point out that more than 15,000 nursing homes are home to roughly 1.4 million seniors each year, and 3.3 million Medicare recipients spend short stays in nursing homes each year.

Mody and Crnich estimated that suspected urinary tract infections account for 30% to 56% of antibiotics that are being inappropriately prescribed, and up to one-third of those prescriptions are for nursing home residents with asymptomatic bacteriuria.

Based on the number needed to harm that Daneman's team calculated in their sensitivity analysis (n=53), Mody and Crnich suggested that close to 20,000 residents of U.S. nursing homes experience an antibiotic-related harm each year by simply living at the facility.

Daneman's group searched through Canadian healthcare databases for nursing home records from 2010 and 2011. To remove potential confounding of data from resident transfers to emergency department or hospital, the researchers created an open-cohort model of the 110,656 adults from 607 nursing homes across Ontario, and tallied antibiotic exposure based on days of use and resident days in the facility.

Daneman's team discovered that out of a total of 50,953,000 possible resident days, antibiotics were administered on 2,783,000 of them. That rate worked out to 55 antibiotic days per 1,000 resident days.

The rate varied quite a bit across facilities, as use ranged from 20.4 to 192.9 antibiotic days per 1,000 resident days.

The classes of antibiotic agents used throughout the different nursing homes were similar, with penicillin and second-generation fluoroquinolones as the most commonly prescribed.

Next, the researchers tracked negative outcomes associated with antibiotic use through ICD-10 codes and claims data. These included Clostridium difficile, diarrhea or gastroenteritis, antibiotic-resistant organisms, and allergic reactions.

Adverse events were more likely to occur in nursing homes in the top-tertile of antibiotic use with 13.3%, but still had high rates in the medium tertile homes at 12.4%. The lowest tertile had a rate of 11.4% of adverse events. (P<0.001).

Daneman's group made a notable finding: the trend toward antibiotic-related adverse events persisted among residents who did not take antibiotics.

For residents who directly received the antibiotics, the risk of adverse events was roughly 1.0% to 1.5% higher in each tertile. For residents who did not receive antibiotics, the risk of an adverse event was 9.9% in the high-use and 8.7% in the low-use tertile (P=0.02)

The risk difference in adverse events between the high and low tertiles translated to a number needed to harm of 53, the authors wrote. But the outright number needed to harm was 71 for direct antibiotic recipients and 83 for nonrecipients.

In a sensitivity analysis, the researchers calculated that for each additional day of antibiotic use in the nursing home, the risk of residents experiencing antibiotic-related harms increased by 0.4% (adjusted OR 1.004, 95% CI 1.001-1.006, P=0.01).

Mody and Crnich found limitations in the study's analytical approach to the study, suggesting that looking at the data by different measures of time, or antibiotic exposure metrics, such as facility-level antibiotic use, would have shifted the results. Also, Daneman's team did not make adjustments for seasonal variation in the use of antibiotics in the current study.

Daneman, Bell, Gruneir, and Bronskill reported financial support from the Canadian Institutes of Health Research.

None of the authors reported any relevant financial relationships with industry.

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